JP2007273204A - Planar lighting apparatus and display device with same - Google Patents

Planar lighting apparatus and display device with same Download PDF

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JP2007273204A
JP2007273204A JP2006096282A JP2006096282A JP2007273204A JP 2007273204 A JP2007273204 A JP 2007273204A JP 2006096282 A JP2006096282 A JP 2006096282A JP 2006096282 A JP2006096282 A JP 2006096282A JP 2007273204 A JP2007273204 A JP 2007273204A
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Keiji Hayashi
啓二 林
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar lighting apparatus which has less variation of a luminous volume of a light-emitting element and is of low manufacturing cost. <P>SOLUTION: An n number of LED elements 13 are connected in series to form an m number of LED rows, and an m number of the LED rows are arranged in parallel between a current output terminal and a current input terminal. When N is for a total number of the LED elements 13 contained in a LED array 12 and n for a total number of the LED elements 13 contained in each of the LED rows, μ for an average of resistance values of the LED elements 13, and T for a predetermined threshold of 0.1 or less, values of N and m are decided to satisfy a formula of √(1/n-1/N)xσ/μ<T. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、面状照明装置、および、面状照明装置を備えた表示装置に関する。   The present invention relates to a planar illumination device and a display device including the planar illumination device.

液晶表示装置などの非発光型の表示装置には、表示パネルの背面に光を照射するバックライトを設ける必要がある。例えば、液晶表示装置には、バックライトとして、冷陰極管（ＣＣＦＬ：Cold Cathode Fluorescent Lamp ）や発光ダイオード（ＬＥＤ：Light Emitting Diode）などが設けられる。バックライトの構造には、エッジライト型と直下型とがある。エッジライト型（サイドライト型とも呼ばれる）のバックライトは、表示パネルの周囲部分に設けられた直線状光源と、直線状光源からの出射光を表示パネルの全面に導く導光板とで構成される。直下型のバックライトは、２次元状に配置された発光素子を含み、表示パネルの全面に光を照射する面状照明装置で構成される。   A non-light emitting display device such as a liquid crystal display device needs to be provided with a backlight for irradiating light on the back surface of the display panel. For example, a liquid crystal display device is provided with a cold cathode fluorescent lamp (CCFL), a light emitting diode (LED), or the like as a backlight. The backlight structure includes an edge light type and a direct type. An edge light type (also called a side light type) backlight is composed of a linear light source provided around the display panel and a light guide plate that guides light emitted from the linear light source to the entire surface of the display panel. . The direct type backlight includes light emitting elements arranged two-dimensionally, and is configured by a planar illumination device that irradiates light on the entire surface of the display panel.

図３は、従来の面状照明装置の構成を示す図である。図３に示す面状照明装置は、定電流電源９１、および、複数のＬＥＤ素子９３を含むＬＥＤアレイ９２を備えている。ＬＥＤ素子９３は複数個ずつ複数の群に分けられ、各群に属する複数のＬＥＤ素子は直列に接続される。定電流電源９１は複数の電流出力端子を有し、各ＬＥＤ列は定電流電源９１の各電流出力端子に接続される。   FIG. 3 is a diagram showing a configuration of a conventional planar illumination device. The planar lighting device shown in FIG. 3 includes a constant current power supply 91 and an LED array 92 including a plurality of LED elements 93. The plurality of LED elements 93 are divided into a plurality of groups, and the plurality of LED elements belonging to each group are connected in series. The constant current power supply 91 has a plurality of current output terminals, and each LED row is connected to each current output terminal of the constant current power supply 91.

ＬＥＤ素子９３に所定以上の電流が流れると、ＬＥＤ素子９３は発光する。このときＬＥＤ素子９３は、ＬＥＤ素子９３の消費電力に応じた輝度で発光する。ところが、ＬＥＤ素子９３の電気−光変換効率には非常に大きなばらつきがあり、ＬＥＤ素子９３の電圧−電流特性（Ｖ−Ｉ特性）にもばらつきがある。このため、ＬＥＤ素子９３の発光量には、ＬＥＤ素子９３の接続形態に依存したばらつきが生じる。このような発光量のばらつきは、各ＬＥＤ列を流れる電流のばらつき、１つのＬＥＤ列内でのＬＥＤ素子の消費電力のばらつき、および、ＬＥＤ素子の電気−光変換効率のばらつきなどに起因する。このようにＬＥＤ素子の発光量にばらつきが生じるために、図３に示す面状照明装置を備えた表示装置では、表示画面に輝度むらや色むらが発生する。   When a predetermined current or more flows through the LED element 93, the LED element 93 emits light. At this time, the LED element 93 emits light with a luminance corresponding to the power consumption of the LED element 93. However, the electro-optical conversion efficiency of the LED element 93 has a very large variation, and the voltage-current characteristic (VI characteristic) of the LED element 93 also varies. For this reason, the light emission amount of the LED element 93 varies depending on the connection form of the LED element 93. Such a variation in the amount of light emission is caused by a variation in current flowing through each LED array, a variation in power consumption of the LED elements in one LED array, a variation in electro-optical conversion efficiency of the LED elements, and the like. As described above, since the light emission amount of the LED element varies, in the display device including the planar illumination device illustrated in FIG. 3, luminance unevenness and color unevenness occur on the display screen.

なお、本願発明に関連する技術として、特許文献１には、ＬＥＤアレイの全体について定電流制御を行うことが開示されている。また、特許文献２には、複数のＬＥＤ素子を直列に接続し、各ＬＥＤ素子に並列に接続した可変抵抗の抵抗値を調整することにより、ＬＥＤ素子の発光量のばらつきを補正することが開示されている。
特開平１１−３０５１９８号公報 特開２００４−２９３７０号公報 As a technique related to the present invention, Patent Document 1 discloses performing constant current control for the entire LED array. Patent Document 2 discloses that a plurality of LED elements are connected in series and a resistance value of a variable resistor connected in parallel to each LED element is adjusted to correct variations in the light emission amount of the LED elements. Has been.
Japanese Patent Laid-Open No. 11-305198 JP 2004-29370 A

しかしながら、特許文献１に記載されたように、ＬＥＤアレイの全体について定電流制御を行っても、ＬＥＤ素子の発光量のばらつきを抑えることはできない。また、特許文献２に記載されたように、複数の光源の輝度を個別に調整する調整手段を設けると、面状照明装置のコストが増大する。   However, as described in Patent Document 1, even if constant current control is performed on the entire LED array, variations in the light emission amount of the LED elements cannot be suppressed. In addition, as described in Patent Document 2, when an adjustment unit that individually adjusts the luminances of a plurality of light sources is provided, the cost of the planar illumination device increases.

それ故に、本発明は、発光素子の発光量のばらつきが小さく、かつ低コストの面状照明装置と、表示画面に発生する輝度むらや色むらを低コストで防止する表示装置とを提供することを目的とする。   Therefore, the present invention provides a low-cost planar illumination device that has a small variation in the amount of light emitted from the light-emitting elements, and a display device that can prevent luminance unevenness and color unevenness generated on a display screen at low cost. With the goal.

第１の発明は、表示装置のバックライトとして使用される面状照明装置であって、
２次元状に配置されたＮ個の発光素子を含む発光素子アレイと、
前記発光素子アレイに対して一定の電流を供給する定電流電源とを備え、
前記発光素子アレイに含まれるＮ個の発光素子はｎ個ずつｍ群に分けられ、各群に属するｎ個のＬＥＤ素子は直列に接続され、これにより形成されたｍ個の回路は前記定電流電源の１対の端子間に並列に接続されており、
前記発光素子の抵抗値の平均をμ、標準偏差をσ、０．１以下に定めた閾値をＴとしたときに、√（１／ｎ−１／Ｎ）×σ／μ＜Ｔを満たすことを特徴とする。 A first invention is a planar illumination device used as a backlight of a display device,
A light emitting element array including N light emitting elements arranged two-dimensionally;
A constant current power source for supplying a constant current to the light emitting element array,
The N light emitting elements included in the light emitting element array are divided into n groups of n, and the n LED elements belonging to each group are connected in series, and the m circuits formed thereby are connected to the constant current. It is connected in parallel between a pair of power supply terminals,
When the average resistance value of the light emitting element is μ, the standard deviation is σ, and the threshold value set to 0.1 or less is T, √ (1 / n−1 / N) × σ / μ <T is satisfied. It is characterized by.

第２の発明は、第１の発明において、
前記発光素子が発光ダイオードであることを特徴とする。 According to a second invention, in the first invention,
The light emitting element is a light emitting diode.

第３の発明は、第１の発明において、
前記閾値Ｔが０．０２であることを特徴とする。 According to a third invention, in the first invention,
The threshold value T is 0.02.

第４の発明は、第１の発明の面状照明装置を表示パネルの背面に設けた表示装置である。   4th invention is the display apparatus which provided the planar illuminating device of 1st invention in the back surface of the display panel.

上記第１の発明によれば、特別な回路を設けることなく発光素子を流れる電流のばらつきを閾値よりも小さく抑え、発光素子の発光量のばらつきを低コストで所定よりも小さく抑えることができる。このような面状照明装置を表示装置のバックライトとして使用することにより、表示画面に発生する輝度むらや色むらを低コストで防止することができる。   According to the first aspect, it is possible to suppress the variation in the current flowing through the light emitting element to be smaller than the threshold without providing a special circuit, and to suppress the variation in the light emission amount of the light emitting element at a lower cost than the predetermined value. By using such a planar illumination device as the backlight of the display device, it is possible to prevent luminance unevenness and color unevenness generated on the display screen at low cost.

上記第２の発明によれば、発光素子として発光ダイオードを備えた面状照明装置について、発光ダイオードを流れる電流のばらつきを閾値よりも小さく抑え、発光ダイオードの発光量のばらつきを所定よりも小さく抑えることができる。   According to the second aspect of the invention, in the planar lighting device including the light emitting diode as the light emitting element, the variation in the current flowing through the light emitting diode is suppressed to be smaller than the threshold value, and the variation in the light emission amount of the light emitting diode is suppressed to be smaller than the predetermined value. be able to.

上記第３の発明によれば、発光素子を流れる電流のばらつきを従来の面状照明装置よりも小さく抑え、発光素子の発光量のばらつきを従来の面状照明装置よりも小さく抑えることができる。   According to the third aspect, the variation in the current flowing through the light emitting element can be suppressed to be smaller than that of the conventional planar illumination device, and the variation in the light emission amount of the light emitting element can be suppressed to be smaller than that of the conventional planar illumination device.

上記第４の発明によれば、面状照明装置では、特別な回路を設けることなく発光素子を流れる電流のばらつきを閾値よりも小さく抑え、発光素子の発光量のばらつきを低コストで所定よりも小さく抑えることができる。このような面状照明装置をバックライトとして備えているので、表示画面に発生する輝度むらや色むらを低コストで防止することができる。   According to the fourth aspect of the invention, in the planar lighting device, the variation in the current flowing through the light emitting element is suppressed to be smaller than the threshold value without providing a special circuit, and the variation in the light emission amount of the light emitting element is lower than the predetermined value at a low cost. It can be kept small. Since such a planar illumination device is provided as a backlight, uneven luminance and uneven color generated on the display screen can be prevented at low cost.

図１は、本発明の実施形態に係る面状照明装置の構成を示す図である。図１に示す面状照明装置１０は、定電流電源１１およびＬＥＤアレイ１２を備えている。ＬＥＤアレイ１２は、ｎ個ずつｍ群に分けられた全部でＮ個（ただし、Ｎ＝ｍ×ｎ）のＬＥＤ素子１３を含んでいる。各群に属するｎ個のＬＥＤ素子１３は、それぞれ直列に接続される。これにより形成されたｍ個のＬＥＤ列は、定電流電源１１の１対の端子間に並列に接続される。具体的には、各ＬＥＤ列の一端は定電流電源１１の電流出力端子に接続され、各ＬＥＤ列の他端は定電流電源１１の電流入力端子に接続される。   FIG. 1 is a diagram illustrating a configuration of a planar illumination device according to an embodiment of the present invention. A planar illumination device 10 shown in FIG. 1 includes a constant current power supply 11 and an LED array 12. The LED array 12 includes a total of N (where N = m × n) LED elements 13 divided into m groups of n. The n LED elements 13 belonging to each group are connected in series. The m LED rows thus formed are connected in parallel between a pair of terminals of the constant current power supply 11. Specifically, one end of each LED row is connected to the current output terminal of the constant current power source 11, and the other end of each LED row is connected to the current input terminal of the constant current power source 11.

図２は、面状照明装置１０を備えた液晶表示装置の構造を示す断面図である。図２に示す液晶表示装置２０では、面状照明装置１０は、直下型バックライトとして液晶パネル２１の背面に設けられている。面状照明装置１０の液晶パネル２１側の表面には光学シート２２が設けられ、反対側の表面には反射シート２３が設けられている。面状照明装置１０からの出射光は、液晶パネル２１の背面の全体に直接に入射する。   FIG. 2 is a cross-sectional view showing the structure of a liquid crystal display device including the planar illumination device 10. In the liquid crystal display device 20 shown in FIG. 2, the planar illumination device 10 is provided on the back surface of the liquid crystal panel 21 as a direct type backlight. An optical sheet 22 is provided on the surface of the planar lighting device 10 on the liquid crystal panel 21 side, and a reflection sheet 23 is provided on the opposite surface. Light emitted from the planar illumination device 10 is directly incident on the entire back surface of the liquid crystal panel 21.

なお、ＬＥＤアレイ１２は、白色に発光するＬＥＤ素子のみを含んでいてもよく、あるいは、赤色に発光するＬＥＤ素子と、緑色に発光するＬＥＤ素子と、青色に発光するＬＥＤ素子とを含んでいてもよい。また、液晶表示装置２０は、面状照明装置１０を１個だけ備えていてもよく、あるいは、複数の面状照明装置１０を備えていてもよい。液晶表示装置２０に複数の面状照明装置１０を設ける場合、複数の面状照明装置１０は、発光面が１枚の平面を形成するように配置される。   The LED array 12 may include only LED elements that emit white light, or LED elements that emit red light, LED elements that emit green light, and LED elements that emit blue light. Also good. Further, the liquid crystal display device 20 may include only one planar lighting device 10 or may include a plurality of planar lighting devices 10. When a plurality of planar illumination devices 10 are provided in the liquid crystal display device 20, the plurality of planar illumination devices 10 are arranged such that the light emitting surface forms one plane.

以下、本実施形態に係る面状照明装置１０の特徴である、ＬＥＤ素子１３の接続形態について説明する。面状照明装置１０は、ＬＥＤ素子１３の総数Ｎと、各ＬＥＤ列に含まれるＬＥＤ素子１３の個数ｎとが次式（１）を満たすことを特徴とする。
√（１／ｎ−１／Ｎ）×σ／μ＜Ｔ …（１）
ただし、上式（１）において、μはＬＥＤ素子１３の抵抗値の平均、σはＬＥＤ素子１３の抵抗値の標準偏差（ばらつき）、Ｔは０．１以下に定めた所定の閾値である。 Hereinafter, the connection form of the LED element 13, which is a feature of the planar illumination device 10 according to the present embodiment, will be described. The planar illumination device 10 is characterized in that the total number N of LED elements 13 and the number n of LED elements 13 included in each LED array satisfy the following expression (1).
√ (1 / n−1 / N) × σ / μ <T (1)
However, in the above formula (1), μ is an average of the resistance values of the LED elements 13, σ is a standard deviation (variation) of the resistance values of the LED elements 13, and T is a predetermined threshold value set to 0.1 or less.

上式（１）を満たす面状照明装置１０によれば、ＬＥＤ素子１３を流れる電流のばらつきを閾値Ｔよりも小さく抑えることができる。以下、その理由を説明する。   According to the planar illumination device 10 that satisfies the above equation (1), the variation in the current flowing through the LED element 13 can be suppressed to be smaller than the threshold value T. The reason will be described below.

ＬＥＤアレイ１２に含まれる１個のＬＥＤ素子（例えば、図１で右上のＬＥＤ素子；以下、ＬＥＤ素子Ｑという）に着目し、ＬＥＤ素子Ｑの抵抗値をｒとする。ＬＥＤ素子Ｑを含むＬＥＤ列には、ＬＥＤ素子Ｑ以外に（ｎ−１）個のＬＥＤ素子１３が含まれている。これら（ｎ−１）個のＬＥＤ素子１３の合成抵抗をＲとする。また、ＬＥＤアレイ１２には、ＬＥＤ素子Ｑを含まないＬＥＤ列が（ｍ−１）個含まれている。これら（ｍ−１）個のＬＥＤ列の合成抵抗をＳとする（図１を参照）。   Focusing on one LED element included in the LED array 12 (for example, the upper right LED element in FIG. 1; hereinafter referred to as LED element Q), the resistance value of the LED element Q is denoted by r. The LED array including the LED elements Q includes (n−1) LED elements 13 in addition to the LED elements Q. The combined resistance of these (n−1) LED elements 13 is R. Further, the LED array 12 includes (m−1) LED rows that do not include the LED element Q. The combined resistance of these (m−1) LED rows is S (see FIG. 1).

ここで、面状照明装置１０を所望の輝度で発光させるためには、各ＬＥＤ素子１３に電流Ｊを流す必要があるとする。この場合、ＬＥＤ列を流れる電流の平均がＪとなるように、定電流電源１１からはそのｍ倍の電流ｍＪが出力される。ＬＥＤアレイ１２全体の合成抵抗はｒ、ＲおよびＳを用いて（ｒ＋Ｒ）Ｓ／（ｒ＋Ｒ＋Ｓ）と表されるから、電流ｍＪを出力する定電流電源１１の両端電圧はｍＪ（ｒ＋Ｒ）Ｓ／（ｒ＋Ｒ＋Ｓ）となる。したがって、ＬＥＤ素子Ｑを含むＬＥＤ列を流れる電流Ｉは、次式（２）で与えられる。
Ｉ＝ｍＪＳ／（ｒ＋Ｒ＋Ｓ） …（２） Here, in order to cause the planar illumination device 10 to emit light with a desired luminance, it is assumed that a current J needs to flow through each LED element 13. In this case, m times the current mJ is output from the constant current power supply 11 so that the average of the current flowing through the LED array is J. Since the combined resistance of the entire LED array 12 is expressed as (r + R) S / (r + R + S) using r, R, and S, the voltage across the constant current power supply 11 that outputs the current mJ is mJ (r + R) S / ( r + R + S). Therefore, the current I flowing through the LED array including the LED element Q is given by the following equation (2).
I = mJS / (r + R + S) (2)

電流Ｉの標準偏差をσI 、合成抵抗Ｒの標準偏差をσR 、合成抵抗Ｓの標準偏差をσS としたとき、誤差伝搬の法則から次式（３）が導かれる。
σI 2＝(∂Ｉ／∂ｒ)2σ2＋(∂Ｉ／∂Ｒ)2σR 2＋(∂Ｉ／∂Ｓ)2σS 2 …（３） When the standard deviation of the current I is σ I , the standard deviation of the combined resistance R is σ R , and the standard deviation of the combined resistance S is σ S , the following equation (3) is derived from the law of error propagation.
σ I 2 = (∂I / ∂r) 2 σ 2 + (∂I / ∂R) 2 σ R 2 + (∂I / ∂S) 2 σ S 2 (3)

Ｎ個のＬＥＤ素子１３の抵抗値は互いに独立であるから、合成抵抗Ｒの標準偏差σR は、１個のＬＥＤ素子１３の抵抗値ｒの標準偏差の√（ｎ−１）倍となる。また、ｎ個のＬＥＤ素子１３の合成抵抗の標準偏差はσ√ｎであり、合成抵抗Ｓの標準偏差σS はその１／√（ｍ−１）3 倍となる。すなわち、次式（４）および（５）が成立する。
σR 2＝（ｎ−１）σ2 …（４）
σS 2＝（ｍ−１）-3ｎσ2 …（５） Since the resistance values of the N LED elements 13 are independent from each other, the standard deviation σ R of the combined resistance R is √ (n−1) times the standard deviation of the resistance value r of one LED element 13. The standard deviation of the combined resistance of the n LED elements 13 is σ√n, and the standard deviation σ S of the combined resistance S is 1 / √ (m−1) 3 times that. That is, the following expressions (4) and (5) are established.
σ R 2 = (n−1) σ 2 (4)
σ S 2 = (m−1) −3 nσ 2 (5)

また、式（２）をｒ、ＲおよびＳでそれぞれ偏微分すると、次式（６）および（７）が得られる。
∂Ｉ／∂ｒ＝∂Ｉ／∂Ｒ＝−ｍＪＳ／（ｒ＋Ｒ＋Ｓ）2 …（６）
∂Ｉ／∂Ｓ＝ｍＪ（ｒ＋Ｒ）／（ｒ＋Ｒ＋Ｓ）2 …（７） Further, when the equation (2) is partially differentiated by r, R and S, the following equations (6) and (7) are obtained.
∂I / ∂r = ∂I / ∂R = −mJS / (r + R + S) 2 (6)
∂I / ∂S = mJ (r + R) / (r + R + S) 2 (7)

式（３）に式（４）〜（７）を代入して整理すると、次式（８）が得られる。

Figure 2007273204
Substituting the equations (4) to (7) into the equation (3) and rearranging results in the following equation (8).
Figure 2007273204

また、合成抵抗ＲはＬＥＤ素子Ｑの抵抗値ｒの（ｎ−１）倍にほぼ等しく、合成抵抗ＳはＬＥＤ素子Ｑの抵抗値ｒのｎ／（ｍ−１）倍にほぼ等しいから、式（８）の（ｒ＋Ｒ）にｎμ、Ｓにｎμ／（ｍ−１）を代入して整理すると、次式（９）が得られる。

Figure 2007273204
The combined resistance R is approximately equal to (n−1) times the resistance value r of the LED element Q, and the combined resistance S is approximately equal to n / (m−1) times the resistance value r of the LED element Q. Substituting nμ for (r + R) in (8) and nμ / (m−1) for S, the following equation (9) is obtained.
Figure 2007273204

さらにｍ＝Ｎ／ｎであるから、電流Ｉの標準偏差をσI は次式（１０）で与えられる。

Figure 2007273204
Further, since m = N / n, the standard deviation of the current I is given by the following equation (10).
Figure 2007273204

上式（１０）の右辺は、上式（１）の左辺のＪ倍に等しい。したがって、上式（１）を満たす面状照明装置１０では、ＬＥＤ素子１３を流れる電流Ｉの標準偏差をσI は閾値Ｔよりも小さいと言える。このように上式（１）を満たす面状照明装置１０によれば、ＬＥＤ素子１３の発光量のばらつきを所定よりも小さく抑えることができる。したがって、面状照明装置１０を備えた液晶表示装置２０によれば、表示画面に輝度むらや色むらが発生することを防止することができる。 The right side of the above equation (10) is equal to J times the left side of the above equation (1). Therefore, in the planar illumination device 10 satisfying the above equation (1), it can be said that σ I is smaller than the threshold value T as the standard deviation of the current I flowing through the LED element 13. Thus, according to the planar illumination device 10 satisfying the above expression (1), the variation in the light emission amount of the LED element 13 can be suppressed to be smaller than a predetermined value. Therefore, according to the liquid crystal display device 20 provided with the planar illumination device 10, it is possible to prevent the occurrence of uneven brightness and uneven colors on the display screen.

面状照明装置１０における閾値Ｔは、従来の面状照明装置において各ＬＥＤ素子を流れる電流の標準偏差（ばらつき）を考慮して決定される。上記の効果を奏するためには、閾値Ｔとして０．１以下の値を用いることが望ましい。一例を挙げると、従来の面状照明装置においてＬＥＤ素子を流れる電流には、約２％のばらつきがあることが知られている。そこで、発光素子の発光量のばらつきを従来の面状照明装置よりも小さく抑えるためには、面状照明装置１０では閾値Ｔとして０．０２を使用すればよい。この場合、ＬＥＤ素子１３の総数Ｎと、各ＬＥＤ列に含まれるＬＥＤ素子１３の個数ｎとの間には、次式（１１）が成立する。
√（１／ｎ−１／Ｎ）×σ／μ＜０．０２ …（１１） The threshold value T in the planar illumination device 10 is determined in consideration of the standard deviation (variation) of the current flowing through each LED element in the conventional planar illumination device. In order to achieve the above effect, it is desirable to use a value of 0.1 or less as the threshold value T. As an example, it is known that the current flowing through the LED element in the conventional planar lighting device has a variation of about 2%. Therefore, in order to suppress the variation in the light emission amount of the light emitting element to be smaller than that of the conventional planar illumination device, the planar illumination device 10 may use 0.02 as the threshold value T. In this case, the following equation (11) is established between the total number N of LED elements 13 and the number n of LED elements 13 included in each LED row.
√ (1 / n−1 / N) × σ / μ <0.02 (11)

また、面状照明装置１０は、特許文献２に記載された面状光源装置とは異なり、発光素子の発光量のばらつきを抑えるために特別な回路などを備えていない。したがって、面状照明装置１０によれば、特別な回路を設けることなく、発光素子の発光量のばらつきを低コストで所定よりも小さく抑えることができる。また、面状照明装置１０を備えた液晶表示装置２０によれば、表示画面に発生する輝度むらや色むらを低コストで防止することができる。   Further, unlike the planar light source device described in Patent Document 2, the planar illumination device 10 does not include a special circuit or the like in order to suppress variations in the light emission amount of the light emitting elements. Therefore, according to the planar illumination device 10, it is possible to suppress the variation in the light emission amount of the light emitting element at a lower cost than the predetermined without providing a special circuit. Moreover, according to the liquid crystal display device 20 provided with the planar illumination device 10, it is possible to prevent luminance unevenness and color unevenness generated on the display screen at low cost.

本発明の実施形態に係る面状照明装置の構成を示す図である。It is a figure which shows the structure of the planar illuminating device which concerns on embodiment of this invention. 図１に示す面状照明装置を備えた液晶表示装置の構造を示す断面図である。It is sectional drawing which shows the structure of the liquid crystal display device provided with the planar illuminating device shown in FIG. 従来の面状照明装置の構成を示す図である。It is a figure which shows the structure of the conventional planar illuminating device.

符号の説明Explanation of symbols

１０…面状照明装置
１１…定電流電源
１２…ＬＥＤアレイ
１３…ＬＥＤ素子
２０…液晶表示装置
２１…液晶パネル
２２…光学シート
２３…反射シート DESCRIPTION OF SYMBOLS 10 ... Planar illumination apparatus 11 ... Constant current power supply 12 ... LED array 13 ... LED element 20 ... Liquid crystal display device 21 ... Liquid crystal panel 22 ... Optical sheet 23 ... Reflection sheet

Claims (4)

表示装置のバックライトとして使用される面状照明装置であって、
２次元状に配置されたＮ個の発光素子を含む発光素子アレイと、
前記発光素子アレイに対して一定の電流を供給する定電流電源とを備え、
前記発光素子アレイに含まれるＮ個の発光素子はｎ個ずつｍ群に分けられ、各群に属するｎ個のＬＥＤ素子は直列に接続され、これにより形成されたｍ個の回路は前記定電流電源の１対の端子間に並列に接続されており、
前記発光素子の抵抗値の平均をμ、標準偏差をσ、０．１以下に定めた閾値をＴとしたときに、√（１／ｎ−１／Ｎ）×σ／μ＜Ｔを満たすことを特徴とする、面状照明装置。 A planar illumination device used as a backlight of a display device,
A light emitting element array including N light emitting elements arranged two-dimensionally;
A constant current power source for supplying a constant current to the light emitting element array,
The N light emitting elements included in the light emitting element array are divided into n groups of n, and the n LED elements belonging to each group are connected in series, and the m circuits formed thereby are connected to the constant current. It is connected in parallel between a pair of power supply terminals,
When the average resistance value of the light emitting element is μ, the standard deviation is σ, and the threshold value set to 0.1 or less is T, √ (1 / n−1 / N) × σ / μ <T is satisfied. A planar illumination device characterized by the above. 前記発光素子が発光ダイオードであることを特徴とする、請求項１に記載の面状照明装置。   The planar illumination device according to claim 1, wherein the light emitting element is a light emitting diode. 前記閾値Ｔが０．０２であることを特徴とする、請求項１に記載の面状照明装置。   The planar illumination device according to claim 1, wherein the threshold value T is 0.02. 請求項１に記載の面状照明装置を表示パネルの背面に設けた、表示装置。   A display device comprising the planar illumination device according to claim 1 provided on a back surface of a display panel.
JP2006096282A 2006-03-31 2006-03-31 Planar lighting apparatus and display device with same Pending JP2007273204A (en)

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Cited By (7)

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CN103024979A (en) * 2011-06-03 2013-04-03 台湾积体电路制造股份有限公司 Architecture for supporting modulized full operation junction UHV LED device
JP2013243085A (en) * 2012-05-22 2013-12-05 Fkk Co Ltd Led lighting fixture
US8866395B2 (en) 2011-08-29 2014-10-21 Panasonic Liquid Crystal Display Co., Ltd. Display apparatus using a backlight
CN104733601A (en) * 2013-12-20 2015-06-24 祯信股份有限公司 Light-emitting diode film circuit board and decoration material
CN104989987A (en) * 2015-06-19 2015-10-21 武汉华星光电技术有限公司 LED light bar, backlight module and liquid crystal display
KR101608256B1 (en) * 2015-11-30 2016-04-01 엘이디코람 주식회사 Light apparatus for multisystem with protection circuit
CN111785216A (en) * 2020-07-03 2020-10-16 业成科技（成都）有限公司 LED array arrangement scheme generation method and device and liquid crystal display module

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103024979A (en) * 2011-06-03 2013-04-03 台湾积体电路制造股份有限公司 Architecture for supporting modulized full operation junction UHV LED device
CN103024979B (en) * 2011-06-03 2016-02-03 晶元光电股份有限公司 Support that the structure of superhigh pressure UHV LED device is tied in complete modularization work
US8866395B2 (en) 2011-08-29 2014-10-21 Panasonic Liquid Crystal Display Co., Ltd. Display apparatus using a backlight
JP2013243085A (en) * 2012-05-22 2013-12-05 Fkk Co Ltd Led lighting fixture
CN104733601A (en) * 2013-12-20 2015-06-24 祯信股份有限公司 Light-emitting diode film circuit board and decoration material
CN104989987A (en) * 2015-06-19 2015-10-21 武汉华星光电技术有限公司 LED light bar, backlight module and liquid crystal display
KR101608256B1 (en) * 2015-11-30 2016-04-01 엘이디코람 주식회사 Light apparatus for multisystem with protection circuit
CN111785216A (en) * 2020-07-03 2020-10-16 业成科技（成都）有限公司 LED array arrangement scheme generation method and device and liquid crystal display module

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